1. Field of the Invention
The invention generally relates to the catheter introducers for intravascular catheterization and more particularly to the catheter insertion apparatus for blood vessel catheterization with a needle tip protective system.
2. Prior Art of the Invention
The catheter introducer for intravascular catheterization includes, as a rule, a catheter having a catheter hub and an axial through channel with a proximal end portion made as a female luer lock portion, a needle assembly comprising a needle with a distal sharp point extending through the catheter axial through channel, and a safety means having a protector for protecting the needle distal sharp point after introducing the catheter into a blood vessel and needle withdrawal from the catheter. In the operation position, the needle is housed inside the catheter through axial channel and the needle distal sharp point protrudes distally from the catheter, allowing the operator the introduction of the catheter into patient's vein. After catheter emplacement, operator withdraws the needle from the catheter unit and closes the catheter hub with a catheter cap, which initially is located separately from the needle assembly. In doing so, the male tapered luer member of the catheter cap occludes the female luer lock portion of the catheter, thereby preventing the catheter from blood leakage and infecting from outside. To close the catheter hub by the catheter cap, operator must release the hand from the withdrawn needle assembly, find the catheter cap, take it with a hand so that its male tapered luer member is faced outwardly, and set it onto the catheter hub. The disadvantage of these operations is that they are inconvenient, take certain time and operator's attention, and do not exclude the infection of the catheter cap. Several attempts to eliminate these disadvantages are known. Specifically, U.S. Pat. Nos. 4,496,348, 4,874,377 and 5,041,097 are disclosed the catheter placement devices with the resilient self-sealing member in the catheter hub, intended for automatic closing the catheter hub after withdrawing the needle. These designs did not find the application because of its high cost and low reliability.
Another disadvantages of known catheter introducers with safety means for protecting the needle distal sharp point can be considered using patent U.S. Pat. No. 4,747,831 as example. This patent discloses a cannula insertion needle set with safety retracting needle, which includes a needle unit having a needle with a distal sharp point and a needle hub, a hollow handle in the form of a barrel for containing a needle unit and protecting the needle distal sharp point in the needle protection position, and a safety means including a latch, a trigger, and a retracting spring disposed inside the barrel. After inserting the cannula (catheter) into patient's vein, operator displaces the latch by means of squeezing or rotating the trigger, thereby releasing the retracting spring, which retracts the needle unit into the protection position inside the barrel. The disadvantage of this cannula insertion set is the complexity of its safety mechanism, wherein the trigger-latch and the barrel are made as separate parts. As a result, the cost of manufacturing and assembling the set is increased. Another disadvantages are the location of the trigger in the zone of the active manipulations of operator's fingers during the cannula emplacement and the direction of the movement needed for the trigger activation. This is inconvenient in operation and decreases the operation reliability creating the danger of inadvertent trigger activation and, as a result, premature retraction of the needle unit into the protection position. The disadvantage is also the considerable impact of the needle hub and the stop member at the end of the needle unit retraction.